Extended Follow-up From the National Lung Screening Trial
Posted: Wednesday, October 16, 2019
Extended follow-up from the National Lung Screening Trial shows a number needed to screen that is similar to the original analysis. In addition, there was no overall increase in lung cancer incidence between low-dose chest computed tomography (CT) and chest radiography. William D. Black, MD, of Geisel School of Medicine at Dartmouth, published these study findings along with colleagues in the Journal of Thoracic Oncology.
The researchers conducted the study by following subjects through linkages to state cancer registries and the national death index. In total, 1,701 patients were diagnosed with lung cancer via low-dose CT, and 1,681 were diagnosed using chest radiography. The number needed to screen to prevent one death was computed by taking the reciprocal of the difference in proportion of patients dying of lung cancer in each arm.
The median follow-up was 11.3 years for incidence and 12.3 years for mortality. There were 1,147 deaths from lung cancer in the low-dose CT–arm and 1,236 in the chest-radiography arm (risk ratio = 0.92). The difference in the number of patients who died of lung cancer across the arms was 3.3 per 1,000; this translates to a number needed to screen of 303, similar to the original number needed to screen of 320. In addition, the dilution-adjusted lung cancer mortality risk ratio was 0.89. In terms of mortality, 5,253 deaths were observed with low-dose CT compared with 5,366 with chest radiography. The difference across the two arms was 4.2 per 1,000.
Disclosure: The study authors’ disclosures can be found at jto.org.